Queens University GEOL 104 | Final Exam

Carbon Dating

Uses properties of radiocarbon to determine the age of an object.

Fossil Succession

A technique used to define the RELATIVE AGE of a fossil.

Relative Age

The age of one feature with respect to another.

Numeric Age

The absolute age of a feature in years.

Paleomagnetism

The study of ancient magnetism preserved in rocks.

Unconformities

Angular Unconformity: Rocks below were tilted or folded before the unconformity developed.

Nonconformity: Sediment rocks overlie older intrusive igneous and/or metamorphic rocks.

Disconformity: Old sedimentary layers erode away overtime, this lasts over a long period of time before new layers of deposition accumulate. This leaves a gap in between time periods.

Stratigraphy

The discipline that studies the layering of rock layers.

A stratigraphic unit is used to describe parts of formations.

Geologic Contact

the boundary surface between two formations. Comparable to other contacts such as faults, unconformities, and intrusive contacts.

Conformable Contact

No time gap between boundary surfaces

Unconformable Contact

There is a Time gap between boundary surfaces.

Isotopic Dating

dating methods based on scientific knowledge about the rate at which various radioactive isotopes of naturally occurring elements transform themselves into other elements by losing subatomic particles.

This rate is CONSTANT.

Stable isotopes do not undergo change overtime, while unstable isotopes undergo radioactive decay by releasing energy but creating a different element.

283U to 206Pb has a half life of 4.5 billion years, roughly the age of Earth!

Orogen

a belt of the earth's crust involved in the formation of mountains. This mountain building leads to deformation in rocks.

Rock Derformation

Displacement: Change in location

Rotation: Change in direction

Distortion: Change in shape
- Stretching
- Shortening
- Shear strain

Deformation Rate

Rapid = Brittle: Atomic bonds break forever and lead to fracturing.

Slow = Ductile: Some bonds break but are quickly reformed allowing for change of shape without fracturing.

Axial Plane

Plane that marks the center of the fold.

Hinge Line

Line where the axial plane intersects with the Earth's surface

Limb

Planar region of a fold that lies on either side of the axial plane.

Strike

Direction taken by a structural surface

Dip

A line perpendicular to strike at an angle of the "slope" to the plane.

Anticline

^ shaped, unfolded sedimentary layers. Oldest strata is towards the centre.

Syncline

V shaped, down folded sedimentary layers. Youngest strata is towards the centre.

Can be symmetrical or asymmetrical.

Dome

Upwarped circular features. Oldest rock is in the centre

Basin

Downwarped circular features. Youngest rock is in the centre.

Monoclines

Large bending folds in otherwise horizontal sedimentary strata.

Tensional Stress

Involves forces pulling in opposite directions, which results in strain that stretches and thins rock

Compressional Stress

when a rock is pressed together into itself

Faults

A fracture on which sliding occurs

Joints

Cracks in rocks that form due to shortening or stretching. Occurs from a variety of ways.

Strike-Slip Fault

Faults that move horizontally.

- Right Lateral
- Left Lateral

Dip-Slip Fault

Faults that move in relation to the angle of the slope.

Normal Faults

A type of dip-slip, where the hanging wall moves down relative to the footwall.

Associated with TENSIONAL STRESS as rocks pull apart.

Reverse Faults

A type of dip-slip, where the hanging wall moves up relative to the footwall.

Associated with COMPRESSIONAL STRESS (shear stress) as the crust shortens.

Horsts

fault blocks bounded by normal faults that are uplifted

Garbens

areas of land bounded by normal faults that have dropped down between faults

Thrust Fault

Have an angle less than 45 degrees, similar to the reverse fault but moves more horizontally-like.

Nappe

A large body of rock that has been moved sideways over other strata.

Autochtonous

Formed in its present position

Allochthonous

Originated at a distance from its present position.

Klippe

Remnant portion of a nappe after erosion has removed the connecting portions of the nappe.

Oblique-Slip Fault

Exhibits both strike-slip and dip-slip fault movements

Fold-thrust belt

When compressional forces lead to crustal shortening and uplift to produce this belt.

Suture

Boundary between blocks that had been separate before the collision

Craton

Crust that has not been affected by orogeny for the last 1 billion years.

Divided into two parts:
- Shields
- Cratonic platforms

Epeirogeny

Vertical movement that creates basins and domes.

Earthquake

Vibrations within or at Earth's surface, resulting due to release of energy from displacement of rocks along faults.

Hypocentre

Where the initial slip of the fault begins, it propagates along the fault surface.

Fault Slip

the amount of displacement on the fault surface

Epicentre

The location on the surface over the hypocenter

Seismology

The study of earthquake waves

Seismographs

Are instruments to record seismic waves

Seismograms

Records that reveal the behaviour of seismic waves within the earth or on the surface.

Body Waves

Can occur at inner and outer layers of the Earth

Primary (P) waves

A type of body wave that compresses and expands to cause destruction. Can pass through ALL states of matter (minus plasma).

Secondary (S) waves

A type of body wave that has shear motion at right angles of their direction of travel.

Surface Waves

seismic waves that can only travel along the Earth's surface

Long (L) waves

Large amplitude. Shake side to side like a snake.

Rayleigh waves

Greatest amplitude, shake up and down like an ocean wave.

Triangulation

Locating the epicentre using multiple seismographs located at different stations.

Divergent Boundary Seismicity

Earthquakes that occur at mid-ocean ridges at shallow depths, have two kinds of faults responsible for tremors:
- Strike-slip
- Normal

Transform Boundary Seismicity

Earthquakes that occur along transform boundaries.

Convergent Boundary Seismicity

Earthquakes can occur at shallow, intermediate, or deep depths.

Possibly a result from the phase change of olivine to spinel (a denser material).

Intraplate Seismicity

5% of seismic energy. Earthquakes occur along ancient, pre-existing faults. Earthquakes here are usually shallow-focus.

Intensity

A measure of the degree shaking caused by an earthquake.

Modified Mercator Intensity Scale

Using buildings to describe the intensity of an earthquake. Does not measure the earthquakes actual severity.

Richter Scale (ML)

Based on the amplitude of the largest seismic wave recorded on the Seismogram. This is able to account for the decrease in wave amplitude as distance increases.

Liquefaction

occurs when an earthquake's violent shaking suddenly turns loose, soft soil into liquid mud.

Is able to create sand volcanoes if there is a layer of loose sand beneath the overlying bed.

Material Amplification

Loose sediments allow for seismic waves to easily pass through in contrast to hard material that weakens the amplitude.

Seiches

Rhythmic sloshing of water in lakes, reservoirs, or enclosed basins.

Regolith

Unconsolidated rocky material

Mass Wasting

This process is fueled by weathering. It's what makes rivers wider, and reshapes mountainous landscapes.

Landslide

Mass movement of rock and/or regolith down a slope.

Based on:
- The type of material
- Speed of movement
- Character of movement
- Environment

Slope Stability

If the driving force (gravity) is greater than the resisting force (friction) then mass wasting will occur.

Forces and effects

- Normal Force
- Downslope force
- Resistance force

If downslope force is less than resistance force, there is no movement.
If downslope force is greater Han resistance force, here is slope movement.

Resistance Force

Produced by chemical bonds, friction, electrostatic attraction, and surface tension of water.

Angle of repose

The steepest possible angle of a slope without collapse.
Varies with material and grain size.

Substrate Weakening

The first step/factor in mass wasting, occurs through jointing, faulting, and weathering.

Slope Stability

The second step/factor in mass wasting, defines the stability of a slope.

Triggering event

The third step/factor in mass wasting, indicates the movement of mass. Gravity's effect increases with:
- Slope angle
- Slope height
- Weight on slope

Undercutting

The removal of support underneath mass. Caused by erosion or excavation.

Water content

The addition of moisture making a SATURATED MATERIAL that literally pushes sediment grains apart.

Creep

Sloe gradual downslope movement of regolith on a slope.

Solifluction

Slow flow of saturated soil downslope indicating no frozen ground is present in the moving layer.

Slumping

Slow moving rock that does not disintegrate but moves as a coherent slump block. Slides along the FAILURE SURFACE

Failure surface

The slope at which the mass slides along. Sometimes planar, but are commonly curved.

Head scarp

The hanging wall that remains above the slump.

Toe

The end of the slump slope where debris piles up

Rock Slide

Sudden movement of rock down a non-vertical slope

Debris slide

Sudden movement of regolith down a non-vertical slope.

Translational Slide

Slide moves along a planar surface.

Rotational

Falls along a curved surface, also known as a slump.

Slide

Movement of material as a coherent block.

Mudflow

A moving slurry of mud

Debris flow

A slurry consisting of mud and larger boulders.

Lamar

Mixture of volcanic ash and water

Rockfalls and debris falls

When mass free falls from a cliff.

Talus

Accumulated debris at the base of a cliff

Submarine slump

in a submarine canyon or on a continental slope, relatively rapid and sporadic downslope composed of sediment and organic debris

Submarine Debris flow

An underwater flow that reaches great size, being one of the largest mass wasting events.

Turbidity currents

a rapid, downhill flow of water caused by increased density due to high amounts of sediment

Erratics

A glacially deposited rock, differing from the surrounding native rocks.